1. Field of the Invention
This invention relates to an apparatus for detecting inhomogeneities in living or dead, human and animal bodies by means of radio-frequency electric voltages and currents of small magnitude. The measured variable is the strength of the electromagnetic field which is established by the radio-frequency electric energy in relation to a reference point (calibrated point) on a measuring member. A relative value is thus measured. At each point on the surface of the body, the field energy has a magnitude which will depend on the route along which the radio-frequency field has traveled in the body and on the conductances/impedances of the media/inhomogeneities that had to be traversed by that field.
One terminal of an alternating current source is directly connected to the body to be examined or is indirectly connected to it by capacitive means and causes said body to radiate like an antenna.
This measuring apparatus comprises a receiving electrode, which is moved towards the surface of the body at the locations where the measurements are to be made, and which measures the strength of the field which is emitted by the body. The two parts of the apparatus consisting of the transmitter and the receiver may be physically separate from each other so that certain advantages will be afforded in the manipulation of the apparatus, e.g., cables can substantially be avoided.
To measure the field strength of the tested body, the receiving electrode (probe electrode) is arranged at a distance from the surface of the body on which a measurement is to be taken at certain locations.
The apparatuses used for such a measuring method must be so designed that the radio-frequency electric energy which is employed will not result in damage to the human body or elsewhere so that the measurement may be repeated, preferably several times and, e.g., the progress or healing of a disease can be followed by means of the measured data and conclusions can be drawn therefrom. Disadvantages of other diagnostic processes, such as X-ray diagnosis, are to be avoided.
The avoiding of damage will also depend on the selection of suitable values for the frequency, voltage and current. An exciting frequency which is near natural frequencies of the body will result in an absorption and will cause the electrically excitable particles to perform natural vibrations. Such vibrations are used, e.g., in microwave therapy equipment for a generation of heat for therapeutic purposes in the tissue. In the use of such apparatus the power which is supplied must carefully be controlled, e.g., in order to prevent burns in the tissue.
The known X-rays, which can destroy cells, have frequencies in a range which is higher than that of a microwave apparatus.
The operating frequency which is used in the above-mentioned radio-frequency diagnosis method lies in a pass band of the cells and cell membranes so that the characteristic impedance has a real value. In the stop bands above and below the pass band the characteristic impedance becomes imaginary and an absorption is effected so that imaginary facts undesirably enter the result of the measurement. In experiments conducted in human bodies for decades it has been found that the frequency limits for useful operation are at 150 kHz on one side and 950 kHz on the other side.
2. Description of the Prior Art
Useful methods or designs are not known in the field of radio-frequency diagnosis. A method having numerous disadvantages has been described in German Patent Specification 950,402, the corresponding laid-open German Patent Application M 7 697 VIII d/30a (and the corresponding French Patent Specification 1,153,724, British Patent Specification 842,863, Swiss Patent Specification 352,781 and U.S. Pat. No. 2,930,977). Reference is also made to G. Bittner, "Uber ein neues Verfahren der Elektrodiagnostik" in Elektromedizin, 6 (1961), 3, pages 125 to 129, where the method discussed in the above-mentioned patent specifications has been described. In a booklet "Physikalische Grundlagen der Antroposkopie, Vorabdruck--auszugsweise--aus Propadeutik der Hochfrequenz-Diagnostik Band I: Wissenschaftliche Grundlagen", issued by Deutsche Gesellschaft fur Hochfrequenz-Diagnostik e.V.--Anthroposkopie--Munich 1986, Paul A. Bross has explained the measuring method in detail. The medical fundamentals have been set forth briefly by R. Kirchhoff in "Physiologische und zytologische Grundlagen fur die Anthroposkopie" in Erfahrungsheilkunde--Zeitschrift fur die arztliche Praxis--acta medica empirica, 29 ( 1980), 8, pages 662 to 664.
Only some important disadvantages of the numerous disadvantages of the known designs will now be set forth:
Under different contact pressures and in different positions of the measuring apparatus (e.g., inclinations) relative to the surface, different values were measured at the same measuring location.
In lines 20 et seq. on page 5, German Patent Specification 950,402 describes a probe having "a contact surface which consists of a material which will not influence the measurement. But such probe cannot be provided in practice because such a material cannot be conceived as every material has a certain specific relative dielectric constant which influences the conductivity for radio-frequency currents. Only air could be used as a "material" having no influence on the measurement because air is also the "material" which surrounds the probe.
That example has been referred to only to facilitate the understanding of the fact that said known method cannot be used in practice if objective data are to be acquired.
Insufficient attention has been directed to the selection of the materials used to make the measuring electrode and, in particular, the significance of the relative dielectric constant of the material for a measurement at a radio frequency has not sufficiently been taken into account so that the results of the measurements taken in the practical use of the apparatuses were not reproducible.
Many of the apparatuses still embodied tube technology and for this reason did not permit some advantages of the measuring method to be achieved.
A further disadvantage resided in the fact that the measurements did not permit an adequate variation because it was difficult or impossible to detect and to correctly interpret inhomogeneities (such as foci of inflammations, on the one hand, or sclerosed tumors, on the other hand) in different depths.
German Utility Model Specification 85 20 235 describes an apparatus for detecting properties, differences and changes of the human living or dead body, comprising an a.c. source, which has one terminal that is directly connected to the body to be examined, and an electric measuring device, which is coupled between the other terminal of the a.c. source and a sensing electrode, which is moved over the surface of the body, wherein spacers are provided on the sensing electrode and the sensing electrode is spaced from that surface of the apparatus which is moved in contact with the body. Within a housing that known apparatus may comprise a shield for preventing disturbing influences to be exerted on an electrode which is spaced from the surface of a body. But that shield must necessarily be disposed within the housing and cannot be removed from that housing. For this reason it is difficult to effect a leakage by a contact with those edges of the shield which face the body, i.e., the tip of the sensing device, so that it is still impossible automatically to detect signals and the correct approach of the apparatus to the body is a difficult operation because it will depend on a visual estimate. Besides, the apparatus cannot be designed to have a high sensitivity and to create a sufficiently small interference at the same time.
U.S. Pat. No. 4,240,445 (see particularly its FIGS. 2 and 3), discloses an apparatus which is of the kind described first hereinbefore and which is provided on its housing with a low superstructure including a strip conductor (electrode) and lateral shields, which surround said strip conductor and are soldered to a shield which also surrounds the strip conductor but is disposed within the housing. An insulating cover layer is also provided. The lateral shields are not provided directly on the housing and do not have a forward edge so that known device does not permit a leakage of the radio-frequency field by a contact with the body to be measured. Besides, the effect of the shield cannot be changed by a variation of the contact pressure between that apparatus and the skin with the result that said effect will be reduced in case of a low contact pressure and will be increased under a higher contact pressure.
German Patent Publication 1,126,559 discloses an apparatus for measuring pulse-synchronized capacitive impedance changes which depend on the blood flow in cell tissues in the depth of hollow organs of human beings or animals, such as the skull, the eye or similar parts of the body. That apparatus comprises electrodes which are connected to a source of radio-frequency energy and uses the pulse-synchronized change of the biological dielectric as a partial capacitance of a radio-frequency resonant circuit in order to modulate the frequency of that circuit. That device comprises sensing electrodes, which have a small surface, and a preferably non-conductive body, particularly a body having an extremely high dielectric constant, is disposed between said electrodes and the object in a manner known per se. That body is surrounded by a covering, which is made of elastic material having a very low dielectric constant. The body and the covering are so designed that they can jointly be forced under a variable pressure against the surface of the object in a manner known per se and said contact pressure is so high that the sphygnoidal changes occurring in the bloodless cell tissue under the contact surface will be suppressed. A radio-frequency voltage is applied in a manner known per se to the electrodes for a determination of the sphygnoidal impedance changes of the dielectric disposed between the electrodes. The measuring circuit is preferably coupled to a resonant circuit of an oscillator to modulate the frequency thereof. But that printed publication relates only to a transmitter. Whereas that transmitter comprises an electrode and lateral shields surrounding said electrode, said electrode and shield are disposed inside a housing and there is no reference to a shield at all in connection with the receiving electrodes.
German Patent Specification 961,827 discloses an electrode array for therapeutic apparatus for the medical treatment effected in a capacitor field of short-wave or ultra-short-wave electric oscillations. In that array the electrode is disposed in a cap (electrode shoe) and is spaced from the surface to be treated, and a second distance can be adjusted in that an adapter (fore-shoe) is mounted in front of the cap. The shell of the cap is slightly tapered and the (bottomless) adapter has the same shape so that the adapter when mounted on the cap will be retained thereon by a wedgelike fit. That cap also constitutes only a transmitter and does not contain a conductive shield.